Double-diaphragm telephone-transmitter



(No Model.) 2 Sheets-Sheet 1.

D. DRAWBAUGH. DOUBLE DIATHRAGM TELEPHONE TRANSMITTER.

N0. 552,469. Patented Deo. 31,1895.

Nrrn TATES DANIEL DRAXVBAUGH, OF EBERLYS MILL, ASSIGNOR TO G. MILTON BAIR, OF HANOVER, AND CALVIN IV. REAM, OF READING, PENNSYLVANIA.

DOUBLE-DIAPHRAGIVI. TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent-No. 552,469, dated December 31, 1895.

Application filed February 23, 1895. Serial No. 539,476. (No model.)

To all whom t may concern.-

Be it known that I, DANIEL DRAWBAUGH, a citizen of the United States, residing at Eberlys Mill, in the county of Cumberland and State of Pennsylvania, have invented certain new and useful Improvements in Double-Diaphragm Telephone-Transmitters and I do hereby declare the following to be a full, clear, and exact description of the inio vention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to telephone-transmitters.

r 5 The object is to produce a microphonetransmitter which shall have increasedresonance and be ready of adaptation and convenient in use.

Vith this object in View, the invention rezo sides, generally, in a microphone-transmitter in which two or more diaphragms, in whole or in part of conductive substance, constituting a double or multiple diaphragm, are arranged in a vocalizing-chamber, edgewise to 2 5 the mouthpiece thereof, a diaphragm at one side connecting with a battery and a diaphragm at the other connecting with the line.

Furthermore, the invention resides in the c-onstruction and details thereof, substantially as hereinafter described and as illustrated by examples in the drawings.

Referring to the drawings, in which two of many forms of embodiment of my invention appear, and in which like letters of ref- 3 5 erence indicate corresponding parts, Figure l is a view in central longitudinal horizontal section showing an arrangement of two diaphragms in a casing constituting the vocalizing-chamber, the diaphragms being wholly of 4o conductive substance separated by a disk of non-conductive substance having a central opening, the diaphragms having centrally within opposing iixed carbon buttons or electrodes between which is granular or powdered carbon retained between the electrodes by 'a disk of sponge or other spongiform--that is, soft, porous, and elastic-substance, having a central openin g for the buttons and set into and fitting in the central opening in the sep- 5o arating-disk, the vocalizing-chamber appearing with its mouth-piece at one end and a vent to the external air at the other, with which the space between the diaphragms communicates, and as pivoted in a bracket and an arm therefrom, showing, furthermore, one diaphragm connected with the wire from battery and external connection from the other diaphragm to line, the internal connection from this diaphragm at a part of the same farthest from the internal connection of the 6o iirst not appearing. Fig. 2 is a view in central transverse horizontal section showing the casing put together in two lateral parts, and

an internal longitudinal circumferential groove in the casing to communicate with the 6 5 vent, and openings or channels in the separative disk from between the diaphragms into the groove, showing, also, the internal connection from the other diaphragm to the external connection to line. Fig. 3 is aview in 7o side elevation of the transmitter in different positions of use and in circuit by spring action and out of circuit by the weight. of a receiver hung upon it, showing the casing with a central lateral disk for eachside having a portion insulated and provided with contacts for the external connections from battery and to line. Fig. 4 is a view in detail of the separating-disk, showing the same with the cent 1al opening holding the sponge havinga cen- 8o tral opening for the carbon buttons to enter and to hold the granular carbon and showing perforations outside the central opening, and

in dotted lines the situation of the channels from one side of the rim of the disk leading to the other side, and, also in dotted lines, another situation in which the channels may be located-namely, from the perforations outward through the circumference. Fig. 5

is another view in central longitudinal hori- 9o Zontal section showing the diaphragms partly of non-conductive and partly of conductive substance and without the separating-disk, the diaphragms being formed each of such a part as would result from taking a disk like 9 5 that shown in Fig. 4, but with a smaller central opening splitting it in two edgewise and turning the faces inward and covering the central opening with metallic plates, showing, furthermore, connection from the batteryroo wire to the conductive part of one diaphragm by a radial metallic strip thereon, and showing the position of the sponge. Fig. G is another view in central transverse horizontal section, and of the device of Fig. 5, showing beyond what is therein displayed, the radial strip from the metallic portion of the other diaphragm to internal and external contact to line; and Fig. 7 is a view in side elevation of one of the diaphragms made partly of noneonductive and partly of conductive substance, showing the radial contactstrip.

Referring to the drawings, A indicates a easing constitutin g a vocalizing-chamber, the same comprisin two parts a and d2, suitably held together, as by providing one of the parts with a circular mortise a3, adapted to be engaged by a circular tenen a arranged on the other part. rlhe chamber is constructed of any suitable material, preferably of hard rubber, and is provided at one end with a threaded portion d, onto which to screw the mouthpiece d6. Arranged longitudinally and centrally of the chamber and clamped in suitable recesses a7 therein are two or more diaphragms B and B2, constructed of any suitable material, and held at a suitable distance apart by means of an insulating and separat-ing disk C. Each of the diaphragms carries a carbon button ZJ and b2, respectively, which project into a circular orifice of an annulus D interposed between the diaphragms and held in place within a circular oriiice c of the disk C, a body of granular carbon E being interposed between the buttons for the purpose of pre` vent-ing make and break of the circuit. The annulus D is constructed of a suitable spongi form material-such as sponge, sponge-rnbber, or any other suitable porous, non conductive material. The casing is provided with an interior circumferential channel as, which connects -with the external atmosphere by means of an orifice a9. The disk C isprovided with a series of openings c2, opening into the channel as, by means of which atmospheric air is admitted t-o the vocalizing-chamber in order to equalize the temperature therein. As shown in Fig. 2,the openings c2 are arranged obliquely to the face of the disk C, but, if desired, the disk may be provided with a series of openings c surrounding the annulus, and from these openings lateral orifices c* project to the periphery of the disk, asindicated by dotted lines in Fig. 4. Asshown in Figs. l and 2, the diaphragms are made wholly of conductive material.

The sides of the casing are provided with trunnions or bearings F, one of which engages a suitable support on the wall or the like, and the other a bracket G, the trunnions being insulated from their supports by means of suitable insulators f. The sides of the casing are further provided with contact-plates Il, whereof a section of each, 7e', is insulated and provided with a contact-point 7b2, one on each side of the casing, the said points being engaged by spring-contact arms I. Then the arms are on the contact-points, .the callcircuit is cut in, but as soon as the telephonereceiver J is detached from the transmitter a spring K draws the transmitter to the position shown in full lines in Fig. 3, in which position the contact-arms are on the uninsulated portion of the contact-plates ll, thus cutting the talking-circuit in. As will. be seen by reference to Fi 3, the insulated portion 7i is of comparatively small size, so that the transmitter may be used at any point from a plane slightly below a horizontal line to an approximately vertical position, thereby accommodating it to persons of different statures.

In Figs. 5 and G the same construction et casing is shown as that illustrated in Figs. Il and 2, and the same means are employed for conducting the current to the diaphragmnamely, spring-contact point-sl and l-which contact, respectively, with contact-points I and i2, connecting through the medium oli' conducting-plates i3 and fi with the diaphragms. The difference of arrangement in the latter figures is in the diaphragms, such difference consisting in the dispensing with the metallic diaphragms of a size practically equivalent to the internal diameter of the vocalizing-chamber and employing in lieu thereof metallic strips M, to which are attached the carbon buttons on. Instead of having the disk C interposed between the diaphragms the same is constructed in two parts, as clearly shown in Figs. 5 and (i, between which the annulus D is held. In operation this particular form of diaphragm will be found to operate as successfully as that form shown in the first two iigurcs, and from a standpoint of simplicity and economy may in some instances be employed to advantage.

In order to prevent the heat from the breath of the person using the telephone from intern fering with the adjustment of the diaphragm,

a shield N is provided at the point of the diaphragm opposite the mouthpiece.

The advantage claimed for this particular construction of telephone and the employment of double diaphragms is that increased resonance is effected, together with capability of greater vibration of the diaphragms, thereby peculiarly fitting this particular form of telephone for effective service in exchange work. The shield N also subserves the further function of dividing the sound so as to cause it to act equally upon both diaphragms to produce equal and synchronous action thereof.

Having thus described my invention, what I claim, and d esire to secure by Letters Patent, is-

l. In a microphone-transmitter in which two or more diaphragms constituting a double or multiple diaphragm arc arranged. in a vocalizing chamber, the combination with the diaphragms carrying carbon buttons, of an interposed insulating disk, a spongiform annulus in which the buttons fit, and a body of granular carbon between the buttons, substantially as described.

IOO

IIO

2. The combination with a multiple diaphragm transmitter, of an insulating disk separating the diaphragrns, a flat elastic or spongiform annulus fitting within an opening in the disk and filling the space between the diaphragms, carbon buttons carried by the diapliragms and fitting in an opening in the annulus, and a body of granular carbon interposed between the buttons, substantially as described. Y

3. A two part vocalizing chamber, diaphragms clamped at their edges between the sections thereof, an insulating and separating disk interposed between and contacting near its periphery with the diaphragms and held in place thereby, a flat spongiforln annulus interposed between and filling the space separating the diaphragins, and engaging an opening in the disk, carbon buttons secured directly to the diaphragms and projecting into an opening in the annulus, and a body of granular carbon interposed between the buttons, substantially as described.

In testimony whereof I affix iny signature in presence of witnesses.

DANIEL DRAWBAUGH. Witnesses:

G. HILTON BAIR, S. G. HOPKINS, E. H. PARRY. 

